Cecilia Ezcurra

Phylogeny of Chuquiraga sect. Acanthophyllae (Asteraceae-Barnadesioideae), and the Evolution of its Leaf Morphology in Relation to Climate

Phylogenetic relationships among the 11 species and subspecies of the Andean-Patagonian Chuquiraga sect. Acanthophyllae were resolved by parsimony cladistic analysis using 22 morphological characters. The comparative method was used to test whether a reduction in leaf width occurred in species due to an adaptation to warmer desert climates. Mean values of annual precipitation, January (summer) temperature and July (winter) temperature were estimated for each taxon. Independent comparisons for leaf width and climatic variables were calculated at each node of the cladogram and a regression analysis of leaf variation versus climatic variation was performed. The probable ancestral geographic area for the group was determined using Bremers method. Results of these analyses suggest that marked involution and reduction in leaf width occurred twice independently in the evolution of the group. Reduction of leaf width was correlated with an increase in temperature. The Puna, Patagonia and the High Andes have the highest probability of having been part of the ancestral area of this section, which currently also extends to the Monte, Prepuna and Chilean Desert. This study suggests a relatively recent climatic effect on the evolution of leaf morphology.

Molecular Phylogeny of Chuquiraga (Asteraceae-Barnadesioideae): Infrageneric Classification and Generic Affinities

Abstract— Chuquiraga is a genus of evergreen shrubs endemic to the arid and semiarid regions of the Andes and southern South America. The genus has been classified into two sections based on its variation in leaf morphology: Chuquiraga and Acanthophylla. Within section Chuquiraga, two series, Chuquiraga and Parviflorae, have been recognized based on variation in size of flower heads. The objectives of this study were to test this classification and to assess the monophyly of Chuquiraga and its intergeneric relationships with the closely related genera Doniophyton and Duseniella. The phylogenetic relationships of 24 of the 27 species and/or subspecies of Chuquiraga (19 of its 22 recognized species), plus 14 species representing seven of the remaining eight genera of Barnadesioideae, and two species of non-barnadesioid Asteraceae were inferred using sequence data from the chloroplast DNA psbA-trnH, rps16-trnK, trnL-rpl32, and/or nuclear ribosomal DNA ITS regions. The plastid and nuclear data sets were analyzed individually and combined, using maximum parsimony, maximum likelihood, and Bayesian inference methods. The phylogenetic results show that Chuquiraga, Duseniella, and Doniophyton form a well-supported monophyletic group, but the relationships among these genera and the monophyly of Chuquiraga are still uncertain. The phylogenies obtained support the monophyly of the sections and reject the monophyly of the series. Section Chuquiraga is divided into two subclades: one includes all species of Chuquiraga series Parviflorae, plus Chuquiraga calchaquina and C. longiflora (of Chuquiraga series Chuquiraga), and the other subclade includes all remaining species of Chuquiraga series Chuquiraga.

A New Species and a New Combination in Matelea (Apocynaceae, Asclepiadoideae) from Southern South America

Abstract Gonolobus foetidus species from southern South America is transferred to Matelea, being characterized by its horizontal pollinia and anthers lacking dorsal appendages (Matelea foetida). A new species, Matelea calchaquina, from arid environments of northwestern Argentina is described and illustrated; data on its habitat, distribution, and phenology is provided. This is a distinctive species within Matelea due to its white flowers with narrow, tubular corollas, which suggest pollination by nocturnal moths. The difficulties in delimiting genera of Gonolobinae based on floral characters are discussed. A key to the species of Matelea from Argentina is included.

A New Species of Oxypetalum (Apocynaceae, Asclepiadoideae) from Northern Argentina

Abstract Oxypetalum is the largest genus of Oxypetalinae (Apocynaceae-Asclepiadoideae) and presents its highest diversity in southern South America. A new species, Oxypetalum globosum, from montane environments of northern Argentina, is described, illustrated, and compared to similar species. Data on its habitat, distribution, ecology, and phenology are provided. This is an outstanding species within Oxypetalum due to its flowers with maroon, globose corollas, with patent, rounded corolla lobes, and a bright pink, exserted, hemispheric stylar-head appendage, which suggest fly- pollination. The difficulties in delimiting genera of Oxypetalinae are discussed. A key to the species of Oxypetalum from northern Argentina is included.